49^ PATAGONIAN EXPEDITIONS : ZOOLOGY. 



disposition to fly diminishes with age. I have arrived at this conclusion 

 after the examination of a number of specimens of volant and non- 

 volant birds, having ascertained from a careful inspection of the condition 

 of the skeleton, and other points in the structure of the volant specimens 

 (the plumage of which entirely corresponded with King's short descrip- 

 tion of Micropterus Patachonicus], that they were all immature individuals 

 (probably the young of the year), and having as invariably found that the 

 non-volant specimens were full grown birds. 



"The colouring of the plumage of the adult bird may be shortly described 

 as follows : The bill is orange-yellow, with the unguis black. The head 

 is cinereous, becoming gradually paler as the individual increases in age, 

 with a small patch beneath the eye, and a streak above it, nearly white. 

 The whole of the upper surface, the throat, the superior part of the breast, 

 and the wings, with the exception of a white speculum, are lead-gray. 

 The lower part of the breast and abdomen vary from a tint verging on 

 primrose-yellow to pale yellowish-white ; and the legs and feet are dark 

 yellow. 



"Younger individuals (M. Patachonicus] are chiefly distinguished by 

 their smaller size, their greenish-black bills, and prevalence of a reddish- 

 brown hue on the throat and scapulars. 



"The average lengths of the adult birds may be stated as about thirty 

 inches, and I do not think that I ever met with specimens measuring more 

 than three feet from the unguis to the tip of the tail ; so that I am inclined 

 to believe that the specimen mentioned by King as forty inches in length 

 was of exceptional size, and I feel no doubt that there must have been 

 some mistake as regards the birds stated by Cook as weighing twenty- 

 nine pounds. 



"The steamer-duck is very plentiful on the shores of the Falkland 

 Islands, in the Strait of Magellan, and in the channels of Western Pata- 

 gonia, as well as at Chiloe, which is the northernmost locality where I have 

 seen it. It is generally to be observed in pairs, or small flocks of six or 

 seven individuals, stationed on the rocks, or swimming about in the exten- 

 sive beds of the 'kelp,' which girdles the coast in many spots; but, occa- 

 sionally, large flocks, composed of many hundreds are to be met with. 

 When undisturbed in the water they swim quietly along, producing two 

 peculiar notes, that of the male being a sort of mew rapidly repeated, 

 while that of the female is a kind of deep growl and diligently search- 



